The availability of DTPA extracted heavy metals during laboratory incubation of contaminated soils with glucose amendments

Abstract

The laboratory incubation with glucose treatment was carried out in order to estimate the possible effects of increased microbial activity on heavy metal availability. The soils from vicinity of a lead smelter operating for more than 200 years were used for the experiment. The DTPA-extractable heavy metal contents increased after glucose addition and mostly reached the highest values the second day of the incubation. The comparative study, where the chloroform fumigation was used prior to the incubation in order to decrease the microbial activities, showed especially from second day of incubation significantly lower DTPA-extractable metal contents compared to non-fumigated treatments. The interactions among the maximum possible availability of DTPA-extractable heavy metal fractions and native soil microbial characteristics were studied in differently contaminated arable and grassland soils. Irrespective of different heavy metal contents in soils, significant correlations were found among the maximum percentage increase of DTPA-extractable Pb and Cd and the ratio Bc/TOC and metabolic quotient (qCO<sub>2</sub>) which may be a result of the important role of organic matter and microbial characteristics in soils on the heavy metal availability.